The advent of computers, interactive electronic communication, the Internet, and other advances in the digital realm of consumer electronics have resulted in a great variety of programming, recording, and viewing options for users who view television programs. A set-top box (STB), for example, is a device that enables a television set to receive and decode both digital and analog television programs. Some STBs can also record television programs; indicate to an analog video recorder, such as a videocassette recorder (VCR), to begin and end recording a television program; insert closed captioning information into the television program; enable the television set to become a user interface to the Internet and perform other functions. STBs are typically necessary to television program viewers who wish to use an analog television set to receive digital broadcasts. STBs are sometimes called receivers. Other devices can perform some of these STB functions such as personal video recorders (PVRs), integrated receiver descramblers (IRDs), satellite receivers, and personal computers. As used hereafter and in the appended claims, unless otherwise specifically denoted, the term “set-top box” will be used to refer expansively to all possible receivers that receive and decode either or both digital and analog television programs.
Some STBs contain a component called a system-on-a-chip (SOC) integrated circuit. The SOC can be an application specific integrated circuit (ASIC), field-programmable gate array (FPGA), or digital signal processor (DSP), for example. The SOC performs a variety of functions and will be explained in more detail below.
Program Delivery Control (PDC) is a data broadcasting system, which carries program-related information for use by STBs. PDC is used in many European countries. In PDC's simplest application, a television program chosen by a user can be recorded by the STB in its entirety, even if the transmission time is different from that published in a program guide. The transmission time could be different if a previous program overruns its allotted time, for example. The PDC data in the signal is used by the STB to extend recording time when necessary. More advanced applications of PDC may, for example, permit recording to be suspended and resumed in synchronism with breaks in television program transmission, such as may occur during a feature film in the event of film breakage.
The functions of the PDC system have been designed mainly around the structure of Video Programming System (VPS) teletext standard data. VPS teletext standard data contains control data that the analog video recorder, such as a VCR, recognizes. Just as PDC allows a STB to digitally record a television program regardless of the program's transmission time, VPS teletext standard data allows the analog video recorder to record a television program regardless of the television program's transmission time.
The VPS teletext standard data is included in a vertical blanking interval (VBI) of the television signal as part of the extended data services (XDS). The VBI is a portion of the television signal that can carry information other than video or audio information.
In many instances, a user desires to use the analog video recorder in conjunction with the STB. For example, the user might have a STB that receives a broadcast television signal and at the same time desires to make a videocassette recording of the broadcasted television program with a VCR. In such a scenario, the VCR would typically receive the VPS teletext standard data via the STB. The STB would have to provide the VPS teletext standard data to the analog video recorder by inserting the VPS teletext standard data into an analog video output of the STB.
However, many STBs are not capable of inserting the VPS teletext standard data into their analog video output because their SOCs do not have state machine support. State machine support allows successful line synchronization in the insertion of the VPS teletext standard data.
One way to insert the VPS teletext standard data into the analog video output of the STB would be to use additional hardware circuitry to generate the necessary line synchronization and data clocks. The additional hardware circuitry would include video encoders, filters, and clocking circuits. This solution is not preferable for a variety of reasons including cost, labor, and potential circuitry failure that would result if additional hardware were installed in pre-existing and new STBs.
Thus, there is a need in the art for a method and system that inserts the VPS teletext standard data into the analog video output of the STB without requiring additional hardware circuitry.